Wrong XAML when using UserControls:

I'm Inserting a Control from another Assembly via DragDrop and XAML Designer is creating wrong xaml:

<Grid Width="2048" Height="1536" Background="White" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

            <Button Content="Button" Grid.Column="0" Grid.Row="0" HorizontalAlignment="Stretch" 
VerticalAlignment="Stretch" Margin="8,8,1965,1505" Width="75" Height="23" />
            <BasicConveyor Grid.Column="0" Grid.Row="0" HorizontalAlignment="Stretch" 
VerticalAlignment="Stretch" Margin="8,40,1910,1346" Width="130" Height="150" 
xmlns="clr-namespace:MCC.VISU.CommonControls;assembly=MCC.VISU.CommonControls" />
        </Grid>

so "Grid.Column" and "Grid.Row" could not be found any more, because the xmlns is overwritten on BasicConveyor

I think the Designer should put the Control in its own namespace:

<Grid Width="2048" Height="1536" Background="White" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
            <Button Content="Button" Grid.Column="0" Grid.Row="0" HorizontalAlignment="Stretch" 
VerticalAlignment="Stretch" Margin="8,8,1965,1505" Width="75" Height="23" />
            <u:BasicConveyor Grid.Column="0" Grid.Row="0" HorizontalAlignment="Stretch" 
VerticalAlignment="Stretch" Margin="8,40,1910,1346" Width="130" Height="150" 
xmlns:u="clr-namespace:MCC.VISU.CommonControls;assembly=MCC.VISU.CommonControls" />
        </Grid>